I noticed Chinese date formatting wasn't working. So I quickly completed zh_CN but also added a generic zh locale. Both contain the same formatting. I am Chinese speaking and did check that there are no mistakes.

I created ​a PR from your branch for review purposes. As we have no Chinese speakers on the cored team as far as I know, could you find a colleague to review the changes and mark the ticket "Ready for Checkin" if it looks okay?